This invention relates generally to electrical switches and in particular to a condition responsive electrical switch, a method of operating a condition responsive electrical switch, and a control system employing a condition responsive electrical switch.
In the past, various types of condition responsive electrical switches have been employed in various environments, and one of the most common of these environments was an appliance, such as a washing machine for instance. The past condition responsive electrical switches were generally automatically operable in response to a certain condition, such as a sufficient reduction in the water level selected for the washing machine, for setting or energizing an electrical circuit for introducing water into the washing machine. When the water attained a selected level in the washing machine, the past condition responsive electrical switch was also generally automatically operable to open a water introducing electrical circuit thereby to terminate the introduction of water into the washing machine and subsequently close another electrical circuit for starting the washing machine. Of course, the condition for effecting such automatic operation of the past condition responsive electrical switches was a differential between the actual water level and an operator selected higher water level, and means were provided for sensing this water level differential to effect the generally automatic operation of the past condition responsive electrical switch. Some of the past condition responsive electrical switches were also provided with operator or manually operated means for overriding the generally automatic operation and resetting the electrical switch thereby to also reset or re-energize the water controlling circuit to again initiate the introduction of additional water into the washing machine.
The manual operation of the past condition responsive electrical switches was effected in several different manners. In some of the past condition responsive electrical switches, a reciprocally movable push rod extended exteriorly of the electrical switch housing for operation by a lever or the like. This push rod was operable generally independently of the other controlling component parts of the condition responsive electrical switch for effecting the resetting thereof and its water controlling circuit. In others of the past condition responsive electrical switches, a manually operable cam was employed to effect the manual resetting operation. The cam was provided with lobes or raised camming or working surfaces between certain positions on the cam for selecting various water levels, and these raised camming surfaces were operable as the cam was manually moved between the certain positions thereof to effect the manual resetting operation of the condition responsive switch either through the component parts thereof or a direct push rod, as previously mentioned.
One of the disadvantageous or undesirable features of some of the past condition responsive electrical switches is believed to be the comparatively large size thereof. This disadvantageous feature was dictated by an analogous disadvantageous or undesirable feature that the means for automatically driving the past condition responsive electrical switches and sensing water level was necessarily rather large in size so as to be sensitive enough to pneumatically sense the differential between water levels in a washing machine. Still another disadvantageous or undesirable feature of some of the past condition responsive electrical switches is believed to be that an operator applied force for effecting the resetting operation thereof was directed through a coiled compression spring thereby to necessitate rather long travel of the means for effecting the resetting operation.